Cellular communications systems typically provide interconnect and/or dispatch voice communication services. Interconnect voice communication services are full-duplex and are typically provided by most cellular or wireless carriers as circuit-switched communications. Dispatch communication services are half-duplex and are commonly known as a walkie-talkie or push-to-talk type of calls such as Sprint Nextel's service identified by the trade name Direct Connect. Interconnect voice communication services provided by most cellular carriers can be provided between sources and destinations of different cellular carriers. However, dispatch communication services are typically implemented in a proprietary manner, which prevents dispatch calls from originating in one cellular carrier's network and terminating in another cellular carrier's network.